Nowadays, solid state lighting elements such as light emitting diodes (LEDs) find many applications due to their attractive properties such as high light output, low energy consumption and long life. For instance, the high light output allows for large areas to be illuminated by a limited number of solid state lighting elements, especially when the solid state lighting elements are combined with an optical waveguide that distributes the output of the solid state lighting elements over a large area.
Due to the cost of solid state lighting elements, there is an incentive to achieve sufficient lighting levels with a minimal number of solid state lighting elements to make the lighting product commercially attractive. However, this is not a straightforward task, as it is far from trivial to avoid losses from optical elements such as optical waveguides that are necessary to achieve the desired light distribution profile.
Different applications may require different types of light distribution. For instance, in modular panel systems such as a suspended ceiling, it may be desirable to produce light of a highly diffuse nature to avoid glare. On the other hand, in domestic applications such as under-shelf or under-cabinet lighting e.g. in kitchens, libraries or reading rooms, it may be desirable to produce light of a more collimated nature.
WO 2012/131636 by the present applicant discloses a solid state lighting strip for mounting in or on a panel support element of a modular panel system. The strip comprises a plurality of solid state lighting elements, a light extraction layer and a glare reducing layer. The solid state lighting elements are arranged such that the light emitted by said elements is coupled into the glare reducing layer via the light extraction layer. The solid state lighting strip can be used as part of a lighting system, a panel support element and a modular panel system.
This lighting strip is particularly suitable for use with low-power side-emitting solid state lighting elements, e.g. side-emitting LEDs, spaced at regular intervals along the light extraction layer to ensure a homogeneous output by the solid state lighting strip. However, this solution is less suitable to generate a collimated light output using a minimal number of solid state lighting elements, and is therefore for instance less attractive for use in applications where such collimation is desirable, e.g. lighting strips for under-shelf or under-cabinet lighting.